01487nas a2200157   4500008004100000022001400041245019400055210006900249260000800318300001200326490000700338520082400345100002401169700001901193856011701212       2018                        eng d  a0022-326300aSolid state auto-inversion of C-centrochirality: enantioselective total synthesis of furocarbazolones (-)-epi-claulansine D and (-)-claulansine D and pyranocarbazolone (+)-epi-claulansine C0 aSolid state autoinversion of Ccentrochirality enantioselective t  cJAN  a382-3870 v833 a<p>Starting from dimethyl (E)-2-{[(1-tert-butoxycarbonyl)-1H-indol-3-yl]methylene}succinate and (R)-2,2,5,5-tetramethyl-1,3-dioxolane-4-carbaldehyde, facile synthesis of (-)-epi-claulansine D was accomplished via condensation and two intramolecular cyclizations. The (-)-epi-claulansine D in the solid state exists in a metastable form, and after an induction period of 30-90 days, it underwent complete epimerization to exclusively deliver the desired natural product (-)-claulansine D in quantitative yield. The witnessed inversion of C-centrochirality in the solid state is conceptually novel and takes place for relatively higher crystal stability reasons. Base-catalyzed ring expansion of both (+/-)/(-)-epi-claulansine D and (+/-)/(-)-claulansine D resulted in (+/-)/(+)-epi-claulansine C in very good yields.</p>1 aMarkad, Shivaji, B.1 aArgade, N., P.  uhttps://library.ncl.res.in/content/solid-state-auto-inversion-c-centrochirality-enantioselective-total-synthesis